Earthbag Cellar – Ventilation Chimney

This seemingly small part of the project turned out to be a place where I immersed myself more than I expected.

The initial objective was to protect the ventilation exhaust pipes from sun (they are made of plastic), rain and rodents. But as it came into being I felt it was a surprisingly prominent aesthetic element that invited me to give it more attention.

I was not able to give this all the attention and quality I wanted because of numerous constraints, especially, in this case, the position of the pipes makes it difficult/precarious to reach.

The first step was to build forms in place (no pictures) and to pour a concrete base.

The next step was to build a brick chimney. I felt comfortable with bricklaying from my experience with rocket stoves. I did experiment with a new (to me) mortar mix (1 lime : 1 concrete : 6 sand). I quickly gave up on trying to lay the bricks perfectly level because of the limited access to the work. I tried to incorporate some anchoring mechanisms into the chimney.

Then it was off to figure out how to design, build and install the head of the chimney. Originally I wanted to create a triangle-shaped roof. But as the chimney came up and took on character in relationship to the cellar, that felt wrong. A more soft and round form appeared in my mind and I set out to draw it … make cutting templates … and finally into the workshop to make it.

First came the base:

… and on top of it … the arch form I envisioned.

After a dry-assembly failed I made a change that would make assembly of the two parts easier … then it was off to char and oil all the wood surfaces:

Next was partially fixing the wire mesh onto the base:

… and initially assembly of the base (to get a sense of progress and make space in the workshop):

Then came the metal-roof preparation. First measuring real sizes and cutting the sheet to size and bending it. I’ve got a slightly tedious but fairly reliable strategy for bending:

In reality it was a sequence of bending and cutting actions that led to a sheet that could be bent and folded onto the curved arch.

… and then mounting it and nailing down the mesh and:

I am not confident that my anchoring strategy has worked ou well … so we will see if this thing holds in high winds or if it will need some reworking next spring!

Tomorrow we hope to get some wood boards that I need for working on the front door … and the earth-floor has set enough that we can carefully walk on it … so it may be possible to also approach the inner door and shelves (without putting them in place yet) … so that when the floor does set we’ll be ready to go!